The present invention relates to an automatic transmission, an automatic transmission control device, an automatic transmission control method, an automatic shift system, and a vehicle using the same.
As a conventional automatic transmission there is used a planetary gear type or parallel-shaft type shift mechanism and there usually is adopted a method wherein a shift is performed by selectively engaging clutches provided individually in gear shift ranges of different transmission gear ratios (see, for example, Japanese Patent Laid-Open No. H10(1998)-89456). The applicant in the present case has proposed such a system as shown in Japanese Patent Application No. 2002-3561245 wherein a parallel-shaft type shift mechanism having two input shafts is combined with a motor to perform a shift actively.
In the system shown in the above application 2002-3561245, gear trains are arranged on two input shafts so as be different in gear ratio to decrease a change in rotation during a shift, whereby the output of a shifting power unit can be decreased. According to this construction, however, the number of gears used becomes twice as large, with a consequent likelihood of an increase of gear noise, mass, and weight.
If the number of gears used is decreased, the output of the shifting power unit will increase.
Further, in the application 2002-3561245, for starting a vehicle driving power unit by the shifting power unit, it is absolutely necessary to engage any of gears connected to an output shaft. Thus, a starting shock is transferred to the vehicle.